Forschungs- & Entwicklungsinformationsdienst der Gemeinschaft - CORDIS

Operative use of satellite derived SCA to update the HBV runoff model during snow melt

Snowmelt is a significant contributor to spring floods in Norway. Updated information of the snow conditions is therefore of major importance to the national flood forecasting. At the Norwegian Water Resources and Energy Directorate (NVE) daily flood predictions are carried out based on runoff simulations using the HBV-model. The HBV model is a lumped rainfall, runoff model which uses precipitation and temperature as input parameters.

In order to improve the spring flood prediction a study testing operational use of satellite-observed SCA (snow covered area) in the HBV-model is carried out. The study includes
- Calibration of HBV-models against both discharge and SCA, and against discharge only, and
- Updating of the HBV-models based on satellite observed SCA.

The results show that the HBV-models calibrated against SCA in addition to discharge simulate discharge as well as models calibrated against discharge only. A success rate of 28 percent was found for the updates of the model. The success and failure of the updates was quite random. However, a weak tendency of higher success rate at large SCA values was found.

A new dynamic snow distribution model was also implemented in the HBV-model. This applies a gamma distribution in which the parameters are functions of the number of accumulation and melting events. In this was the modelled spatial distribution of SWE (snow water equivalent) more closely follows the observed spatial distributions of SWE. HBV-models with the new snow distribution model predicts discharge as good as the traditional snow distribution model, predicts SCA better and gives a consistently improved prediction of the discharge when updating the model for satellite derived SCA.

Reported by

Norwegian Water Resourses and Energy Directorate, Section for Water Balance
P.O.Box 5091 Majorstua
0301 Oslo
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